氮氧化铝(AlON)是一种透明高硬度防弹材料,可以由反应Al2O3+C+N2 高温__ 2AlON+CO合成,下列有关说法正确的是( )
They had a difficult time _______ in the village at first, but soon they got over it.
拉萨和重庆纬度相近,气温相差很大,其主要因素是( )
五四运动标志着中国革命进入新民主主义革命时期,主要是因为此后( )